not considered to be part of either the field preceding or the field
following.
+@item -T @var{tempdir}
+@opindex -T
+@cindex temporary directory
+Use directory @var{tempdir} to store temporary files, overriding the
+@env{TMPDIR} environment variable. If this option is given more than
+once, temporary files are stored in all the directories given. If you
+have a large sort or merge that is I/O-bound, you can often improve
+performance by using this option to specify directories on different
+disks and controllers.
+
@item -u
@opindex -u
@cindex uniquifying output